Heretofore, there has been a vehicle seat which comprises a back frame provided inside a seat back to support a headrest.
For example, JP-U (Japanese Utility Model Laid-Open Publication) 07-001842 (Hereinafter simply ‘PTL1’) discloses an automobile seat in which a back frame is provided with an impact pressure-receiving frame and a headrest support frame. The impact pressure-receiving frame has a lower end swingably attached to a lower portion of the back frame. On the other hand, the headrest support frame has a vertically central portion swingably attached to an upper portion of the back frame, and a lower end coupled to an upper end of the impact pressure-receiving frame. That is, the headrest support frame is configured such that it is swingingly moved to allow an upper end thereof to be moved frontwardly, in interlocking relation to a rearward inclining movement of the impact pressure-receiving frame.
Thus, during a rear impact event, as the impact pressure-receiving frame is pushed and inclined rearwardly by an occupant, the headrest supported by the upper end of the headrest support frame is moved frontwardly, so that a gap between a head of the occupant and the headrest is reduced to protect the occupant's head.
However, in the PTL 1, the back frame is provided with two frames consisting of the impact pressure-receiving frame and the headrest support frame, and configured to allow the two frames to interlock with each other, which causes a problem of structural complexity.
The present invention has been made to solve the above problem, and an object thereof is to provide a vehicle seat capable of protecting a head of an occupant during a rear impact event with a simple structure.